Hello and welcome, I am glad you stumbled upon this forum because it is a great place, full of support and full of people just like you.
How do you do it? Well, you just decide to stop and you stop, but of course it isn't that easy. One thing for sure is that you must get a plan in place to address this issue and start to fight it.
For me it took taking a month off of my life and going to rehab. Generally that is a last resort for people and most balk at the idea- I know I did until there really was no other option left for me.
The thing I want to tell you more than anything though is that it is entirely possible. There are so many avenues of support out there- AA, SMART meetings, this forum, rehab, doctors, etc. And then there is you, and you are stronger than you know. You can do this, it won't always be easy, but it is possible.
Have you spoken to your psychiatrist about this? My real journey began when I spoke to my psychiatrist about my alcoholism. My work with him helped to an extent, but as I mentioned, I needed the additional step of going to rehab to cut the cycle and really start down the path of sobriety. You may be able to do this without rehab, but I would think that a serious and very honest talk with your psychiatrist would be a good starting point.
Keep the dialogue going and share with us, we are all here to support you and advise you.